This invention relates to a novel apparatus and a novel process for producing gel beads of microbial cells or enzyme, particularly gel beads of microbial cells or enzyme enclosed in gels.
A technique of producing gel beads of microbial cells or enzyme by suspending microbial cells or enzyme in a colloidal solution such as an alginate solution, a carrageenan solution, etc., dispersing the colloidal suspension into a droplet state, and contacting the droplets of the colloidal suspension with a gelling agent such as an aqueous calcium chloride solution or an aqueous potassium chloride solution has been so far widely utilized in the production of gel beads of immobilized microbial cells or immobilized enzyme by gel enclosure.
Heretofore, dispersion of a colloidal suspension of microbial cells or enzyme in a colloidal solution, which will be hereinafter referred to merely as "colloidal suspension", into a droplet state and contacting of the droplets of the colloidal suspension with a gelling agent are carried out according to a nozzle trickling method. However, the nozzle tricking method has such problems as larger sizes of produced gel beads and restriction to the capacity to produce gel beads. An improvement of the nozzle tricking method is proposed in Japanese Patent Application Kokai (Laid-Open) No. 57-186446. The proposed improvement is to provide an air purging around a trickling nozzle for a colloidal suspension, where an increased capacity to produce the gel beads can be expected. However, a large number of nozzles are required for increasing the capacity to produce the gel beads and also it is necessary to supply a sterilized air as the purging air. Thus, the structure and operation are complicated. Furthermore, to produce gel beads of smaller bead size, it is necessary to use nozzles of smaller size. Such nozzles are liable to be clogged and mass production cannot be assured.
On the other hand, a method for forming uniform droplets by breaking up a jet stream of a colloidal suspension, using a resonance technique, is proposed [Biotechnology and Bioengineering, 27, June (1985), 870-876]. However, the proposed method requires a special device for resonance and is not suitable for mass production of gel beads.